Check valve, sealing bag, and production methods for both

ABSTRACT

To provide a check valve and a sealing bag that are high in certainty of the checking effect and prevented as much as possible from increasing in the production cost. 
     A check valve V includes base sheets  31  and  32 , made of a flexible resin, and a plurality of valve body sheets  4 , at least two of the valve body sheets  4 , that is, an upstream valve body sheet  4   a  and a downstream valve body sheet  4   b  form a single set and both are adhered to one base sheet  31 , the adhesion of the upstream valve body sheet  4   a  to the one base sheet  31  is achieved at an upstream end  4   a   1  side with a downstream end  4   a   2  side being movable with respect to the base sheets  31  and  32 , the adhesion of the downstream valve body sheet  4   b  is achieved at a downstream end  4   b   2  side with an upstream end  4   b   1  side being movable with respect to the base sheets  31  and  32 , and the respective ends  4   a   2  and  4   b   1  of the valve body sheets  4   a  and  4   b  at the sides made movable with respect to the base sheets  31  and  32  are closely contactable with the other base sheet  32.

FIELD OF THE ART

The present invention relates to a check valve, a sealing bag thatincludes the check valve, a method for producing the check valve, and amethod for producing the sealing bag.

From before, there have been sealing bags with which an articlecontaining portion that includes a space for containing clothing, food,or other article can be sealed in a gastight state. With such a sealingbag, a check valve connecting the article containing portion and anoutside of a bag in a ventable manner is used to evacuate air andvarious other gases present in the article containing portion to theoutside of the bag and maintain the evacuated state.

In the evacuation of gas, the check valve can allow passage of gas flowin one direction while blocking gas flow in another direction by openingand closing of a gas flow passage space that is a space through whichthe gas passes.

A conventional example of a check valve includes a check valve describedin Patent Document 1. As shown in FIG. 10, with this check valve 100,respective lower edges of a plastic film 101 of rectangular shape and ashorter filtering film 102 of the same width are overlapped, and loweredges of plastic films 103 and 104 are overlapped with an upper edge ofthe filtering film 102 and further overlapped with one surface of theplastic film 101 to form a flat laminate, and both side edges and alower edge of the laminate are adhered by heating. The upper edge of thefiltering film 102 and a lower edge overlapped portion 100 a of theplastic films 103 and 104 are then adhered by heating to form a gasrelease flow path 108 with respect to the plastic film 103 whileproviding an opening portion 106 at an upper end and providing afiltering surface 107 made of the filtering film 102 at one surface of alower portion. A checking piece 103 a is then formed with the plasticfilm 103, an actuating pocket portion 109 therefor is provided, and alow-viscosity inert liquid is coated onto an upper inner surface of theplastic film 101 or an inner surface of the check valve 103 to maintainclose contact of the film surfaces.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Published Unexamined Patent Application No.H9-112721

SUMMARY OF THE INVENTION Objects of the Invention

However, with the check valve 100 of the conventional example describedabove, only a single checking piece 103 a is provided, and a gas flow ina reverse direction is blocked by close contact of the plastic film 101and the checking piece 103 a. That is, the close contact is achievedonly at a single location and certainty of the checking effect is thuslacking. Coating of the low-viscosity inert liquid was thus essentialfor improving the checking effect in the invention according to PatentDocument 1.

Also obvious in improving the above, a structure must be arranged thatwould prevent increase of the production cost of the check valve as muchas possible.

Also, as a desirable function of a check valve, minimizing of “initialpressure,” which is gas pressure inside a sealing bag at an instant atwhich evacuation is started, can be cited. This is because when the“initial pressure” is high, evacuation is not started readily and largeexternal force must be applied to the sealing bag or gas may remaininside the bag without being evacuated readily so that the sealing bagswells in a clumsy manner.

The present invention has been made in view of the above and an objectthereof is to provide a check valve that is improved in certainty of thechecking effect, is prevented as much as possible from increasing in theproduction cost, and is small in “initial pressure,” and to provide asealing bag that includes the check valve and methods for producing thecheck valve and the sealing bag.

Means for Achieving the Object

To achieve the above object, an aspect of the present inventionaccording to claim 1 provides a check valve formed by overlapping aplurality of sheets, having a gas flow passage space 3 a, which is aspace through which gas passes, formed between the sheets, and beingcapable of allowing passage of gas flow in a positive direction from aninlet to an outlet and blocking gas flow in a reverse direction from theoutlet to the inlet by opening and closing of the gas flow passagespace, wherein the check valve is comprised of a plurality of basesheets 31 and 32 made of resin, and a plurality of flexible valve bodysheets 4 made of resin;

-   -   the plurality of base sheets 31 and 32 being disposed to face        each other in a front/back direction,    -   at least two sheets of the plurality of valve body sheets 4        forming a single set comprising an upstream valve body sheet 4 a        disposed at an upstream side and a downstream valve body sheet 4        b disposed at a downstream side on a basis of the positive gas        flow direction,    -   each of the valve body sheets 4 a and 4 b that forms the single        set being adhered to at least one base sheet 31,    -   the adhesion being achieved so that the respective valve body        sheets 4 a and 4 b are aligned in series in a gas flow direction        during evacuation and so as not to be overlapped in the        front/back direction,    -   the adhesion of the upstream valve body sheet 4 a to the one        base sheet 31 being achieved at an upstream end 4 a 1 side with        a downstream end 4 a 2 side being made movable with respect to        the base sheets 31 and 32,    -   the adhesion of the downstream valve body sheet 4 b being        achieved at a downstream end 4 b 2 side with an upstream end 4 b        1 side being movable with respect to one base sheets 31 and 32,        and    -   at least a portion of the single set of valve body sheets 4 a        and 4 b being capable of contacting closely and separating with        respect to another base sheet 32 or with respect to a valve body        sheet 91 different from the single set of valve body sheets 4 a        and 4 b and disposed on the opposite side of the one base sheet        31 across the single set of valve body sheets 4 a and 4 b,        thereby allowing passage of gas flow in the positive direction        and block gas flow in the reverse direction.

An aspect of the present invention according to claim 2 provides thecheck valve according to claim 1, wherein

-   -   a portion of the one base sheet 31 is arranged as a gas flow        passage portion 31 a having gas permeability of allowing gas        flow in the positive direction to pass through in the front/back        direction,    -   the gas flow passage portion 31 a being an inlet through which        the gas flow in the positive direction flows into the check        valve, and    -   the gas flow passage portion 31 a being disposed at a position        of the one base sheet 31 that is further upstream than a        position matching the upstream end 4 a 1 of the upstream valve        body sheet 4 a in the front/back direction.

An aspect of the present invention according to claim 3 provides thecheck valve according to claim 2, wherein

-   -   the one base sheet 31 comprises the gas flow passage portion 31        a and another portion, the another portion having gastightness.

An aspect of the present invention according to claim 4 provides thecheck valve according to claim 1, wherein the outlet 32 b through whichgas flow in the positive direction flows out from the inside of thecheck valve is disposed at other exterior sheet 32 side,

-   -   the outlet 32 b being formed by making the other exterior sheet        32 smaller than the one exterior sheet 31 or by providing    -   an opening in the other exterior sheet 32, and the outlet 32 b        being disposed at a position of the one base sheet 31 that is        further downstream than a position matching the downstream end 4        a 2 of the upstream valve body sheet 4 a in the front/back        direction.

An aspect of the present invention according to claim 5 provides thecheck valve according to claim 4, wherein

-   -   bent seals s4 and s5 are formed between the inlet 31 a and the        inlet 31 a,    -   the bent seals s4 and s5 being adhesion of the one base sheet        31, the valve body sheets 4, and the other base sheet 32 in the        front/back direction, and    -   the bent seals s4 and s5 shaping bent so that a flow path inside        the check valve V from the inlet 31 a to the inlet 31 a becomes        a zigzagging flow path in a plan view of the sheets.

An aspect of the present invention according to claim 6 provides thecheck valve according to claim 5, wherein

-   -   a silicone liquid or other inert substance 8 is disposed inside        a flow path, defined by the bent seals s4 and s5, between the        valve body sheets 4 and the other base sheet 32.

An aspect of the present invention according to claim 7 provides thecheck valve according to claim 1, wherein

-   -   the one base sheet 31 has gas permeability across its entire        surface,    -   a portion of the gas-permeable one base sheet 31 is arranged as        a gas flow passage portion 31 a through which gas flow in the        positive direction passes in the front/back direction,    -   the gas flow passage portion 31 a being a portion of the one        base sheet 31 that is further upstream than a position matching        the upstream end 4 a 1 of the upstream valve body sheet 4 a in        the front/back direction.

An aspect of the present invention according to claim 8 provides thecheck valve according to claim 2, wherein

-   -   the gas flow passage portion 31 a of the one base sheet 31 is        provided with a nonwoven fabric.

An aspect of the present invention according to claim 9 provides thecheck valve according to claim 1, wherein

-   -   the one base sheet 31 is made of a nonwoven fabric having gas        permeability across its entire surface,    -   a portion of the gas-permeable one base sheet 31 is arranged as        a gas flow passage portion 31 a through which gas flow in the        positive direction passes in the front/back direction,    -   a portion of the one base sheet 31 except the gas flow passage        portion 31 a abeing covered by a covering sheet 92 having        gastightness.

An aspect of the present invention according to claim 10 provides thecheck valve according to claim 1, wherein the check valve is used bybeing fixed to a sealing bag 1 having an article containing portion 2,the article containing portion 2 being capable of ventilation to theoutside of the bag to evacuate gas present in the article containingportion 2 to the outside of the bag.

An aspect of the present invention according to claim 11 provides asealing bag 1 having the check valve V according to claim 4 fixedthereto,

-   -   wherein the sealing bag 1 is comprised of a flexible bag sheets        11 and 12 made of resin,    -   the bag sheets 11 and 12 being adhered so that a portion except        an article receiving opening 1 a and a portion to which the        check valve V is fixed is separated in a gastight manner from        the outside of the bag, and    -   a whole perimeter of the check valve V is adhered to an inner        side or an outer side of the bag sheets 11 and 12.

An aspect of the present invention according to claim 12 provides asealing bag 1 having the check valve V according to claim 7 fixedthereto,

-   -   wherein the sealing bag 1 is comprised of a flexible bag sheets        11 and 12 made of resin,    -   the bag sheets 11 and 12 being adhered so that a portion except        an article receiving opening 1 a and a portion to which the        check valve V is fixed is separated in a gastight manner from        the outside of the bag,    -   the check valve V, sandwiched by the bag sheets 11 and 12,        having an upstream end positioned inside the article containing        portion 2 and a downstream end positioned outside the article        containing portion 2 on a basis of a gas flow direction during        evacuation,    -   a portion at an upstream end side of the other base sheet 32 of        the check valve V being adhered to a surface of the bag sheets        11 and 12 that is an inner surface facing the other base sheet        32,    -   a gas flow passage portion 31 a of the one base sheet 31 of the        check valve V being exposed to a space in the article containing        portion 2 that is capable of containing an article,    -   a lateral direction seal 13 being formed by adhesion of the bag        sheets 11 and 12,    -   the lateral direction seal 13 being formed to traverse the check        valve V in a width direction,    -   a longitudinal direction seal 14 being formed additionally by        the adhesion of the bag sheets 11 and 12,    -   the longitudinal direction seal 14 being in a direction        intersecting the lateral direction seal 13 and extended more to        the upstream side than the lateral direction seal 14 on a basis        of a gas flow direction during evacuation inside the check valve        V,    -   the longitudinal direction seal 14 being provided sandwiching        the check valve V and being spaced by an interval wider than a        width dimension of the check valve V to form a single set by        two, and    -   an upstream end 141 of the longitudinal direction seal 14 being        positioned further upstream, on a basis of the gas flow        direction during evacuation inside the check valve V, than a        lower end 31 a 1 of a portion, of the gas flow passage portion        31 a in the one base sheet 31, which is defined by the lateral        direction seal 13 and through which air practically flows.

An aspect of the present invention according to claim 13 provides amethod for producing the check valve according to claim 1, whereinelongate sheets supplied continuously in a longitudinal direction areused as the base sheets 31 and 32 and the valve body sheets 4, and

-   -   the respective valve body sheets 4 a and 4 b forming a single        set are supplied as a single elongate sheet that is thereafter        cut in two in a width direction and overlapped with the one base        sheet 31.

An aspect of the present invention according to claim 12 provides amethod for producing a sealing bag 1 having a check valve V fixedthereto,

-   -   wherein the check valve V is comprised of flexible base sheets        31 and 32 made of resin; and a plurality of valve body sheets 4,    -   one base sheet 31 of the base sheets 31 and 32 has gas        permeability across its entire surface,    -   the base sheets 31 and 32 are disposed to face each other in a        front/back direction,    -   at least two sheets of the plurality of valve body sheets 4        forming a single set comprising an upstream valve body sheet 4 a        disposed at an upstream side and a downstream valve body sheet 4        b disposed at a downstream side on a basis of a gas flow        direction during evacuation,    -   each of the valve body sheets 4 a and 4 b that forms the single        set are adhered at least to the one base sheet 31,    -   the adhesion is achieved so that the respective valve body        sheets 4 a and 4 b are aligned in series in the gas flow        direction during evacuation and so as not to be overlapped in        the front/back direction,    -   the adhesion of the upstream valve body sheet 4 a to the one        base sheet 31 is achieved at an upstream end 4 a 1 side with a        downstream end 4 a 2 side being made movable with respect to the        base sheets 31 and 32,    -   the adhesion of the downstream valve body sheet 4 b is achieved        at a downstream end 4 b 2 side with an upstream end side 4 b 1        being movable with respect to the base sheets 31 and 32, and    -   the respective ends 4 a 2 and 4 b 1 of the valve body sheets 4 a        and 4 b that are made movable with respect to the base sheets 31        and 32 are capable of closely contacting the other base sheet 32        or a valve body sheet 4 that is different from the valve body        sheets forming the single set and is adhered to the other base        sheet 32; and    -   a flexible elongate sheet made of resin and supplied        continuously in a longitudinal direction is used as bag sheets        11 and 12,    -   the method for producing a sealing bag comprising the steps of:    -   sandwiching the check valve V by the bag sheet 11 and 12;    -   forming a lateral direction seal 13 traversing the check valve V        in a width direction by adhesion of the bag sheets 11 and 12;        and    -   forming a longitudinal direction seal 14 by adhesion of the bag        sheets 11 and 12;    -   the longitudinal direction seal 14 formed in the steps, being in        a direction intersecting the lateral direction seal 13 and        extended more to the upstream side on the basis of the gas flow        direction during evacuation inside the check valve V than the        lateral direction seal 14,    -   the longitudinal direction seal 14 being provided sandwiching        the check valve V and spaced by an interval wider than a width        dimension of the check valve V to form a single set by two, and    -   an upstream end 141 of the longitudinal direction seal 14 being        positioned further upstream, on a basis of the gas flow        direction during evacuation inside the check valve V, than a        lower end of a portion 31 a 1, of the gas flow passage portion        31 a in the one base sheet 31, which is defined by the lateral        direction seal 13 and through which air practically flows.

Effects(s) of the Invention

The present invention can provide a check valve that is improved incertainty of the checking effect, is prevented as much as possible fromincreasing in the production cost, and is small in “initial pressure,”and provide a sealing bag that includes the check valve and methods forproducing the check valve and the sealing bag.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a check valve according to an embodiment of the presentinvention with FIG. 1A being a plan view, FIG. 1B being an end viewviewed in a direction of arrows X-X in FIG. 1A, and FIG. 1C being abottom view.

FIG. 2 is a schematic view, with principal portions being exaggerated,of a relationship of another base sheet and valve body sheets in thecheck valve of the same embodiment and showing a state where a gas flowpassage space is closed.

FIG. 3A is a plan view of a sealing bag of the same embodiment and FIG.3B is a plan view of principal portions of an example where a shape of alongitudinal direction seal in the sealing bag of the same embodiment ischanged.

FIG. 4 is a schematic view of a transverse section of a cul-de-sacportion during evacuation in the sealing bag of the same embodiment.

FIG. 5 shows schematic views of a state where the check valve accordingto the above embodiment is fixed to a sealing bag according to anotherembodiment of the present invention with FIG. 5A being a perspective ofa back surface side of the bag, FIG. 5B being a longitudinal sectionalview at the position of the check valve of the back surface side of thebag, and FIG. 5C being a transverse sectional view at the positionindicated by arrows Y-Y of FIG. 5B of the back surface side of the bag.

FIG. 6A is a front view of a sealing bag according to another embodimentof the present invention, FIG. 6B is a front view of a sealing bagaccording to still another embodiment of the present invention, and FIG.6C is a central longitudinal sectional view of the sealing bag of FIG.6B.

FIG. 7A is a sectional view of a check valve according to anotherembodiment of the present invention, FIG. 7B is a plan view of the samecheck valve, FIG. 7C is a bottom view of the same check valve, FIG. 7Dis a structural explanatory diagram of a state where the same checkvalve is fixed to an inside of a sealing bag, and FIG. 7E is astructural explanatory diagram of a state where the same check valve isfixed to an outside of a sealing bag.

FIG. 8A is a plan view of a check valve according to still anotherembodiment of the present invention, FIG. 8B is a bottom view of thesame check valve, FIG. 8C is a sectional view of the same check valve,FIG. 8D is a structural explanatory diagram of a state where the samecheck valve is fixed to an inside of a sealing bag, and FIG. 8E is asectional view of a check valve according to still another embodiment.

FIG. 9A is a sectional view of a check valve according to still anotherembodiment and FIG. 9B is a sectional view of a check valve according tostill another embodiment.

FIG. 10 is a longitudinal sectional view taken along a longitudinaldirection of a check valve according to a conventional example.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention shall now be described based on thedrawings.

Expressions indicating positions and directions, such as “front andback,” “upper, lower, right, and left,” “longitudinal and lateral,” “oneand other,” etc., written in the claims and specification of the presentinvention are used for the sake of description and specification and theapplicant has no intention to limit the present invention to modes ofthe positional relationships as described.

Also, the expressions of “upstream and downstream” are based on apositive direction (direction of gas flow during evacuation along alongitudinal direction of a check valve V) .

A sealing bag 1 according to the present embodiment may be used as adeaeration bag that can be reduced in volume by evacuation of gaspresent in an article containing portion 2. Examples of specificapplications of the deaeration bag include a food pack for food storage(that exert a freshness keeping effect in storage upon lessening of airinside a bag) and a compression bag for clothing (that can be reduced involume by lessening of air inside a bag) that are used for evacuatingthe air present in the article containing portion 2. Implementation as abag containing in the article containing portion 2, for example, coffeebeans, powder detergent, or other article that generates gas andenabling evacuation of the gas generated from the article to an outsideof a bag to suppress expansion of the bag is also possible.

In order to evacuate the gas present in the article containing portion 2to the outside of the bag as described above, a check valve V thatallows passage between the article containing portion 2 and an outsideof a bag is fixed to the sealing bag 1. Although in the present example,a single check valve V is provided per single sealing bag 1, the presentinvention is not limited thereto and a plurality of check valves V maybe provided per single sealing bag 1.

As shown in FIG. 3A, the sealing bag 1 of the present example includes afront bag sheet 11 and a back bag sheet 12 that are made of flexibleresin and are overlapped and oriented in a front/back direction, and bythe bag sheets 11 and 12 being adhered (heat sealed) together, a portionexcept an article receiving opening 1 a and a portion to which the checkvalve V is fixed is separated from the outside of the bag in a gastightmanner. The check valve V is fixed by being sandwiched by the bag sheets11 and 12 in the front/back direction. The check valve V may also besandwiched by only one of the bag sheets 11 and 12 by the one bag sheetbetween the bag sheets 11 and 12 being folded back, etc. Also, althoughin the present example, two resin sheets of the same rectangular shapein a plan view are overlapped in the front/back direction as bag sheets11 and 12, the bag may be provided with a gusset at a side surface andthe shape of the bag sheets may be a shape other than a rectangular.Also, a zipper of a known arrangement is provided at the articlereceiving opening 1 a to enable opening and closing in a gastightmanner. However, such a zipper enabling opening and closing isunnecessary with a bag that contains coffee beans or a sealing bag of atype that is finally closed by adhesion of the article receiving opening1 a by a heat sealer.

The check valve V allows passage of a gas flow in a positive directionand blocks a gas flow in a suctioning direction by opening and closingof a gas flow passage space 3 a that is a space through which a gaspasses during evacuation of the gas from the article containing portion2 of the sealing bag 1.

As shown in FIGS. 1A and 1C, a shape in a plan view (bottom view) of thecheck valve V of the present example is a rectangular shape that islonger in a longitudinal direction dimension than a width dimension, andthe gas flow passes in the longitudinal direction.

The check valve V includes one base sheet 31 and another base sheet 32that are made of flexible resin and a plurality of valve body sheets 4.

Resin sheets with the same width dimension are used as the base sheets31 and 32 and these are disposed to face each other in the front/backdirection. In regard to the longitudinal direction dimension, the onebase sheet 31 is longer than the other base sheet 32 (actions andeffects thereof shall be described later). The base sheets 31 and 32 areoverlapped in the front/back direction with upstream sides (left endsides in FIG. 1) being aligned.

The valve body sheets 4 are overlapped while being sandwiched by thebase sheets 31 and 32. Both edges in the width direction and an upstreamside edge in the longitudinal direction of the respective base sheets 31and 32 are adhered (heat sealed) and closed in a gastight manner. Theadhesion at both edges in the width direction is performed on all of thebase sheets 31 and 32 and the valve body sheets 4. As shall be describedbelow, in the present example, a nonwoven fabric is used as the one basesheet 31 and thus a gas flow inlet of the check valve V is a gas flowpassage portion 31 a (described below) of the one base sheet 31. As thenonwoven fabric, that which is without scuffing and is excellent inwater resistance and durability, such as a spunbonded nonwoven fabricformed by melting a thermoplastic polymer and ejecting in a continuous,long fibrous form is preferable. Also, by using filaments with acore-sheath structure that uses a fiber with strength, such aspolyester, inside and polyethylene, which is comparatively soft and canbe subject to heat sealing and other forms of processing, outside,strength and processability can be realized at the same time. The gasflow passage portion 31 a is an inlet 31 a through which the gas flow inthe positive direction flows into the check valve V. On the other hand,an outlet 32 b is a downstream end portion in a longitudinal directionof the check valve V (more precisely, a portion between an edge of theother base sheet 32 and the one base sheet 31), wherein gas flow in thepositive direction flows out from the check valve V.

In the present example, a point seal 5 is formed at a width directioncenter of the check valve V as shown in FIG. 1C and the base sheets 31and 32 and the valve body sheets 4 are adhered thereat. In the presentexample, the point seal 5 is formed as a short heat seal extending in alongitudinal direction of the check valve V. The point seal 5 isprovided for rectifying the gas flow during evacuation but is notessential to the present invention and does not have to be formed.

Among the plurality of valve body sheets 4, at least the two sheets ofan upstream valve body sheet 4 a disposed at an upstream side and adownstream valve body sheet 4 b disposed at a downstream side form asingle set.

In the present example, sheets (plastic films) of the same material andthickness are used as the other base sheet 32 and the valve body sheets4. As the sheets 32 and 4, “self-close-contacting” sheets (films) areused that can readily be closely contacted with counterpart sheets thatare facingly disposed. As shall be described below, a nonwoven fabric isused as the one base sheet 31. However, the arrangements of therespective sheets are not limited to those of the present example, and,for example, in a case where the base sheets 31 and 32 are exposed tothe outside of the sealing bag 1, the base sheet 32 maybe arranged as asheet that is thicker than the valve body sheets 4.

Both valve body sheets 4 a and 4 b forming the single set are adhered toonly the one base sheet 31. In a case where three or more valve bodysheets 4 are included, a valve body sheet 4 may also be adhered to theother base sheet 32. However, even in this case, adhesion of both of thevalve body sheets 4 a and 4 b forming the single set to at least the onebase sheet 31 is an essential condition of the present invention.

The adhesion of the respective valve body sheets 4 a and 4 b forming thesingle set to the one base sheet 31 is performed so that the valve bodysheets 4 a and 4 b are disposed in series with respect to the gas flowdirection inside the valve during evacuation and so that both valve bodysheets do not overlap in the front/back direction.

The adhesion of the upstream valve body sheet 4 a to the one base sheet31 is achieved at an upstream end 4 a 1 side. The adhered portion isindicated as s1 in FIG. 1B. A downstream end 4 a 2 side of the upstreamvalve body sheet 4 a is made movable with respect to the base sheets 31and 32.

Also, the adhesion of the downstream valve body sheet 4 b is achieved ata downstream end 4 b 2 side. The adhered portion is indicated as s2 inFIG. 1B. An upstream end 4 b 1 side of the downstream valve body sheet 4b is made movable with respect to the base sheets 31 and 32. In thepresent example, the downstream end 4 b 2 of the downstream valve bodysheet 4 b is matched with the downstream end 31 b of the one base sheet31.

That is, by the adhesion of the valve body sheets 4 a and 4 b beingachieved as described above, respective free ends of the valve bodysheets 4 a and 4 b are disposed in a mutually facing manner on the onebase sheet 31.

An interval between the valve body sheets 4 a and 4 b is preferably anextremely small interval made by forming a slit by cutting a singlesheet with a cutting blade as described later. By forming such anextremely small interval, a step is not present between the valve bodysheets 4 a and 4 b, and even when a nozzle, etc., is inserted into thedeaeration valve V during evacuation, catching of the nozzle, etc., willnot occur.

The free ends, that is, the respective ends 4 a 2 and 4 b 1 of the valvebody sheets 4 a and 4 b that are made movable with respect to the basesheets 31 and 32 are made closely contactable to the other base sheet32. When the close contact is not achieved, gaps are formed between therespective valve body sheets 4 a and 4 b and the other base sheet 32 andthe gas flow passage space 3 a is open as shown in FIG. 1B.

The other base sheet 32 is flexible and thus when the gas flow passagespace 3 a is open as described above, the other base sheet 32 is movedto a lower side in FIG. 1B by evacuation pressure. Smooth evacuationwithout clogging of the gas flow passage space 3 a in the middle is thusachieved.

In this process, even if the downstream valve body sheet 4 b and theother base sheet 32 happen to be put in a difficult-to-separate state(due to such a cause as dew condensation, etc.), the evacuation is notmade difficult because the evacuation gas flow can pass from between therespective ends 4 a 2 and 4 b 1 of the valve body sheets 4 a and 4 b andthrough an exposed portion 31 c (a portion positioned at the outside ofthe article containing portion 2 when the check valve V is fixed to thesealing bag 1) of the one base sheet 31.

On the other hand, when the article containing portion 2 becomes lowerin pressure in comparison to the outside of the bag, negative pressure farises inside of the check valve V as shown in FIG. 2. The respectivevalve body sheets 4 a and 4 b are lifted away from the one base sheet 31by the negative pressure f. “Self-close-contacting” sheets are used asthe other base sheets 32 and the valve body sheets 4 a and 4 b asdescribed above and thus by the lifting away, the mutually facing sheetsbecome closely contacted reliably. When the close contact is achieved,the gaps between the respective valve body sheets 4 a and 4 b and theother base sheet 32 are eliminated and the gas flow passage space 3 a isclosed.

In this process, a gas flow s, tending to flow in reverse through thecheck valve V from the exposed portion 31 c of the one base sheet 31,may flow in as indicated by arrows in FIG. 2. In this case, therespective valve body sheets 4 a and 4 b are pressed against the otherbase sheet 32 by the gas flow s tending to flow in reverse and thesheets are closely contacted even more reliably. The gas flow passagespace 3 a is thus closed even more reliably.

In the present example, the valve body sheets 4 a and 4 b arerespectively closely contacted with the other base sheet 32 as shown inFIG. 2. That is, the close contact is achieved at two locations andcertainty of the checking effect is thus improved in comparison to thearrangement of check valve described in Patent Document 1. Coating of alow-viscosity inert liquid is thus not essential as in the inventionaccording to Patent Document 1. An advantage in terms of the productioncost of the check valve is thus provided. However, a low-viscosity inertliquid (for example, silicone oil, etc.) may be coated for the purposeof further increasing the certainty of the checking effect.

In a case where a valve body sheet 4 is also adhered to the other basesheet 32, the valve body sheets 4 a and 4 b are respectively closelycontacted with the valve body sheet 4 adhered to the other base sheet32.

In the present example, the one base sheet 31 to which the valve bodysheets 4 a and 4 b forming the single set are adhered has gaspermeability across its entire surface. More specifically, in thepresent example, the one base sheet 31 having gas permeability is anonwoven fabric.

A portion of the one base sheet 31 is arranged as the gas flow passageportion 31 a through which the gas flow during evacuation passes in thefront/back direction. The gas flow passage portion 31 a is the portionof the one base sheet 31 that is further upstream than a positionmatching the upstream end 4 a 1 of the adhered upstream valve body sheet4 a in the front/back direction.

Although the one base sheet 31 has gas permeability across its entiresurface, a valve supporting portion 31 b that is a portion overlappedwith the respective valve body sheets 4 a and 4 b in the front/backdirection is not a portion through which a gas flows as in the gas flowpassage portion 31 a in the state where the check valve V is fixed tothe sealing bag 1 (however, the gas flow passing between the ends 4 a 2and 4 b 1 of the respective valve body sheets 4 a and 4 b can passthrough as described above).

In the present example, the one base sheet 31 is a nonwoven fabric andthus even at the valve supporting portion 31 b, the surface facing thevalve body sheets 4 a and 4 b is a rough surface. Thus, even if thevalve body sheets 4 a and 4 b are “self-close-contacting” sheets asdescribed above, the sheets can detach readily from the one base sheet31.

Although conventionally to make a valve body sheet detach readily in theabove manner, a coating material is coated on the surface of the basesheet facing the valve body sheet, with the arrangement of the one basesheet 31 of the present example, the need to coat a coating material iseliminated. The present arrangement is advantageous in terms of theproduction cost of the check valve from this aspect as well.

However, it is not essential for the one base sheet 31 to have a gaspermeability across its entire surface as in the present example. Onlythe gas flow passage portion 31 a may be made gas permeable by using asheet having gas permeability only at a portion or by attaching togethera sheet with gas permeability and a sheet without gas permeability. Evenin such cases, it is preferable, for making the valve body sheets 4 aand 4 b readily detachable from the one base sheet 31, to form a roughsurface at the valve supporting portion 31 b by corona dischargetreatment, etc.

As described above, the downstream end 4 b 2 of the downstream valvebody sheet 4 b in the present example is matched with the downstream end31 b of the one base sheet 31. In the present example, the one basesheet 31 is longer in a longitudinal direction dimension than the otherbase sheet 32 and the upstream sides of the base sheets 31 and 32 arealigned. Thus, a portion of the downstream valve body sheet 4 b that isfurther downstream than a position matching the downstream end 32 a ofthe other base sheet 32 in the front/back direction is arranged as anon-contacting portion 4 b 3 that does not overlap with the other basesheet 32 in the front/back direction.

If such a non-contacting portion 4 b 3 is not provided and thedownstream edges of the check valve V are matched in the front/backdirection, the arrangement is readily influenced by distortions(waviness) occurring in the sheets and reverse flow due to capillaryaction occurs readily. The distortion tends to be more significantcloser to an edge and thus in the present example, the position at whichone sheet is closely contacted with another sheet is shifted so as toavoid an edge, and by arranging the other base sheet 32 and thedownstream valve body sheet 4 b to contact closely as shown in FIG. 2,the influence of the distortion is reduced. Thus, reverse flow can alsobe prevented effectively by providing the non-contacting portion 4 b 3.

The check valve V arranged as described above has an upstream endpositioned inside the article containing portion 2 of the sealing bag 1and a downstream end positioned outside the article containing portion2. In regard to a positional relationship of the check valve V withrespect to the sealing bag 1, although the downstream end of the checkvalve V may protrude out from an edge of the sealing bag 1, in thepresent example, the check valve V is fixed so that the downstream endof the check valve V is positioned closer to the article containingportion 2 than the edge of the sealing bag 1 as shown in FIGS. 3A and3B. That is, with the check valve V in the present example, the entirevalve is sandwiched by the bag sheets 11 and 12. The check valve V isthereby protected by the bag sheets 11 and 12 and thus comparativelythin sheets (plastic films) may be used as the base sheets 31 and 32.Also, the sealing bag 1 is good in appearance and an obstacle due to aprotruded check valve V is not presented during storage of the sealingbag 1, etc., because the check valve V can be arranged so as not toprotrude from the edge of the sealing bag 1. A point seal 15 shown inFIGS. 3A and 3B is formed by the bag sheets 11 and 12 being adhered tounify the bag sheets 11 and 12 at a downstream side of the check valve Vand may be omitted.

In the present example, a heat seal for adhering the bag sheets 11 and12 has a stepped shape as shown in FIGS. 3A and 3B. The articlecontaining portion 2 is thereby formed so as to have a partially notchedform. The check valve V is disposed at the notched portion. Although inthe present example, the “notch” is formed at a corner portion of thesealing bag 1 that is rectangular in a plan view so as to enable use ofa widest portion of the article containing portion 2 as possible, thepresent invention is not limited thereto and, for example, a “notch” maybe formed at a center of an end portion of the sealing bag 1 if requiredby design.

Of the bag sheets 11 and 12, an inner surface of either bag sheet 11 or12 at the side that faces the other side base sheet 32 is adhered to aportion at the upstream end of the other base sheet 32 of the checkvalve V. In the present example, adhesion to the back bag sheet 12 isachieved by forming of a valve fixing seal 6 as shown in FIG. 4, and thegas flow passage portion 31 a of the one base sheet 31 of the checkvalve V is thereby exposed to a space in the article containing portion2 that is capable of containing an article. Although in the presentexample, the valve fixing seal 6 is provided in a line-like form at bothends in the width direction of the check valve V as shown in FIG. 1C, itsuffices that the check valve V is able to follow deformation of theback bag sheet 12 and the positional relationship, shape, and quantitymay be changed variously as shown in FIG. 4. However, in order to makethe check valve V be aligned effectively along an inner surface of acul-de-sac portion 21 that takes on an arched form as shall be describedlater, it is preferable to provide the valve fixing seal 6 at adownstream side in the gas flow direction relative to the upstream end141 of a longitudinal direction seal 14. By the gas flow passage portion31 a being exposed as described above, air that is present in thearticle containing portion 2 can be guided readily to the check valve Vto enable evacuation to be performed smoothly.

Also, a lateral direction seal 13 is formed in the sealing bag 1 by theadhesion (heat sealing) of the bag sheets 11 and 12 to each other. Thelongitudinal direction seal 14 and the traversing seal 13 do notindicate longitudinal and lateral positions of the sealing bag 1 and thebag sheets 11 and 12, and simply a direction along theupstream/downstream direction of the check valve V is defined as thelongitudinal direction and a direction intersecting this is defined asthe lateral (traversing) direction.

The lateral direction seal 13 is formed to traverse the check valve V inthe width direction and more specifically, is formed further downstreamthan the upstream end 4 a 1 of the upstream valve body sheet 4 a.Although the lateral direction seal 13 is formed rectilinearly in a planview in the present example as shown in FIGS. 3A and 3B, it may beformed to have a wavy shape instead. A wavy shape is advantageous inthat in this case, evacuation pressure is applied non-uniformly in thewidth direction to the check valve V during the evacuation of air,thereby facilitating the opening of the gas flow passage space 3 a.

Also with the present example, a release coating 7 is coated onto aninner surface of the other base sheet 32 at a portion at which thelateral direction seal 13 is formed, and a situation where the otherbase sheet 32 and the upstream valve body sheet 4 a become lightlyadhered due to heat during forming of the lateral direction seal 13,which is a heat seal, and disable smooth evacuation can thereby beavoided. As an alternative to the release coating 7, a nonwoven fabricmay be attached to the inner surface of the other base sheet 32.

In addition to the lateral direction seal 13, the longitudinal directionseal 14 is formed in the sealing bag 1 by the adhesion (heat sealing) ofthe bag sheets 11 and 12 to each other. The longitudinal direction seal14 extends in a direction intersecting (in the present example, adirection orthogonal to) the lateral direction seal 13 and extendsfurther upstream than the lateral direction seal 14 on a basis of thegas flow direction during evacuation of the inside of the check valve V.The longitudinal direction seal 14 is formed as a single set of the twoseals of an inner longitudinal direction seal 14 a and an outerlongitudinal direction seal 14 b that are spaced by an interval widerthan a width dimension of the check valve V so as to sandwich the checkvalve V. In the present example, the outer longitudinal direction seal14 b formed at a right side of the check valve V in FIGS. 3A and 3Bserves in common as a side seal formed at an edge of the sealing bag.Also in the present example, the inner longitudinal direction seal 14 aand the lateral direction seal 13 are formed at the same time by asingle sealing bar (heat bar).

The upstream end 141 of the longitudinal direction seal 14 is positionedfurther upstream, on the basis of the gas flow direction during theevacuation of the inside of the check valve V, than a lower end 31 a 1of a portion, of the gas flow passage portion 31 a in the one base sheet31, which is defined by the lateral direction seal 13 and through whichair practically flows. In regard to the positional relationship of theupstream end of the check valve V and the upstream end 141 of thelongitudinal direction seal 14, the upstream end 141 is preferablydisposed at a position more downstream than the upstream end of thecheck valve V in the gas flow direction. In the present example, theupstream end 141 of the inner longitudinal direction seal 14 a isdisposed at substantially the same position as the upstream end of thecheck valve V in the gas flow direction as shown in FIG. 3A. Also, evenin a case where the upstream end 141 is disposed further downstream thanthe upstream end of the check valve V, it is preferable to make adistance between the upstream end 141 and the upstream end of the checkvalve V as small as possible so that a larger portion of the gas flowpassage portion 31 a is overlapped with the cul-de-sac portion 21 thattakes on the arched form as shall be described later.

Also, although in the present example, the inner longitudinal directionseal 14 a is formed to be continuous in an up/down direction in thefigures, for example, gas passing gaps 14 c, indicated by a broken linein FIG. 3A may be provided or the inner longitudinal direction seal 14 amay have a discontinuous form as shown in FIG. 3B. In such cases, thecul-de-sac portion 21 that is deformable to the arched form as shall bedescribed later is formed and in the article containing portion 2, airpresent at a portion to the left of the inner longitudinal directionseal 14 a in the figures can be guided to the check valve V through thegas passing gaps 14 c to enable smooth evacuation.

The cul-de-sac portion 21 is formed by the lateral direction seal 13 andthe longitudinal direction seal 14. The cul-de-sac portion 21 swells sothat its transverse section takes on an arched form as shown in FIG. 4when the article containing portion 2 is compressed with hands or wheninternal pressure increases due to generation of gas from the containedarticle. The check valve V is adhered to the back bag sheet 12 asdescribed above and thus the check valve V is aligned with an innersurface of the cul-de-sac portion 21 that has taken on the arched form.

During evacuation, air in the article containing portion 2 is firstguided to the cul-de-sac portion 21 and is thereafter successivelyevacuated out of the bag through the gas flow passage portion 31 a. Onthe other hand, in a case where such a cul-de-sac portion 21 is notformed, an interval between the bag sheets 11 and 12 may not spreadsufficiently during evacuation and an evacuation fault may occur. Such aproblem does not occur when the cul-de-sac portion 21 is formed, and theevacuation can be performed more smoothly and the “initial pressure” canalso be reduced thereby.

Here, with a conventional sealing bag, a check valve is difficult toopen, and to reduce the “initial pressure,” the check valve is disposedat an end portion of the sealing bag and the base sheets and the valvebody sheets of the check valve are distorted intentionally. Although the“initial pressure” can thereby be reduced, there is a problem thatreverse flow also occurs readily. In contrast, the check valve Vaccording to the present invention enables smooth evacuation on its own,is not limited in a position of fixing to the sealing bag 1, and canthus increase a degree of freedom of design of the sealing bag 1.

A method for producing the check valve V shall now be described.Elongate sheets supplied continuously in a longitudinal direction areused as the base sheets 31 and 32 and the valve body sheets 4. Therespective valve body sheets 4 a and 4 b forming the single set aresupplied as a single elongate sheet, which is then cut in two in a widthdirection by application of a cutting blade and then overlapped with andadhered to the one base sheet 31. By the cutting, a slit is formed inthe single elongate sheet that is the material of the valve body sheets4. The overlapping is performed immediately after the forming of theslit and the valve body sheets 4 a and 4 b are adhered while theinterval therebetween is maintained as an extremely small interval.Thus, in comparison to a case where different sheets are supplied as thematerials of the respective valve body sheets 4 a and 4 b, the checkvalve V can be produced more simply and with higher precision and theproduction cost also does not increase.

Due to convenience of design of a production apparatus, etc., incontrast to the above, the valve body sheet 4 supplied as a singleelongate sheet may first be overlapped with the one base sheet 31 and acutting blade may thereafter be applied to the valve body sheet 4 in theoverlapped state to cut the sheet in two in the width direction to formthe valve body sheets 4 a and 4 b.

The check valves V are produced in a state of being joined in the widthdirection and are cut individually in a process of fixing to the sealingbag 1. However, the valves may also be fixed to the sealing bag 1 ascontinuous valves in a state where a plurality of valves remaincontinuous in the width direction.

A method for producing the sealing bag 1 with the check valve V fixedshall now be described briefly. Elongate sheets made of a flexible resinand supplied continuously in a longitudinal direction are used as thebag sheets 11 and 12. The method for producing the sealing bag 1includes the steps of sandwiching the check valve V by the bag sheets 11and 12, forming the lateral direction seal 13 by adhering the bag sheets11 and 12, and forming the longitudinal direction seal 14 likewise byadhering the bag sheets 11 and 12. Sealing bags with check valves can beproduced continuously by the present production method.

As another embodiment, the check valve V may be fixed not restrictedlyto a bag such as shown in FIG. 3A but may be fixed to a so-called“vertical pillow” type sealing bag 201 such as shown in FIG. 5A that isoften used as packaging for coffee beans, etc. The respective figures ofFIG. 5 show an article-contained state. In FIG. 5C, an inner side of thebag is drawn as an upper side in the figure and an outer side of the bagis drawn as a lower side in the figure.

In producing such a “vertical pillow” type sealing bag 201, a single bagsheet 211 is folded over at crease lines 212 and 212 at both right andleft sides of the bag, edges of the bag sheet 211 are matched at a backsurface side (to put the sheet in a folded state), and the check valve Vis sandwiched and adhered between the facing edges, and a seal therebyformed is used as the lateral direction seal 13. Then as shown in FIGS.5B and 5C, portions of the bag sheet 211 are made to enter furtherinward into the sealing bag 201 than the lateral direction seal 13 andadhered together to form a seal. The seal functions as the longitudinaldirection seal 14. In the example shown in FIG. 5B, an auxiliary seal 16extending parallel to the lateral direction seal 13 in an oppositedirection to the check valve V is provided at an upstream end of thelongitudinal direction seal 14 and gas inside the bag can thereby beguided effectively to the cul-de-sac portion 21.

Even with the “vertical pillow” type sealing bag 201, the cul-de-sacportion 21 is formed by the lateral direction seal 13 and thelongitudinal direction seal 14 as in the bag shown in FIG. 3A, and in acase where the internal pressure of the bag increases, a transversesection of the cul-de-sac portion 21 swells so as to be an arched form(see FIG. 4). Thus, in the same manner as described above, evacuationcan be performed smoothly and the “initial pressure” can be reduced withthe sealing bag 201 as well. Thus, in a case where the contained articleis coffee beans or other article that constantly generates gas (carbondioxide, etc.), the sealing bag 201 does not swell clumsily due to thegenerated gas not being evacuated readily to the outside of the bag andremaining in the bag.

Although with the example shown in FIG. 3, the check valve V is disposedat a bottom portion of the sealing bag 1, the position at which thecheck valve V is disposed may be changed as suited and may be a sideportion of the sealing bag 1 or a central portion (a front surface or aback surface) of the sealing bag 1.

In an example shown in FIG. 6A, the check valve V is disposed at aposition close to the article receiving opening 1 a at a side portion ofthe sealing bag 1. In this example, a recessed portion 211 is formed byrecessing the bag sheets 11 and 12 in the lateral direction and thecheck valve V is sandwiched and fixed in a laterally extending manner atthe position close to the article receiving opening 1 a equipped with azipper. The recessed portion 211 is, the bag sheets 11 and 12 aresealed, and

A seal at an inner side of the recessed portion 211 is theabove-described lateral direction seal 13. With the present example, ina case where a liquid matter is contained or in a case where a food,etc., that releases a liquid is contained, the liquid matter stays at abottom of the bag and thus by disposing the check valve V at theposition close to the article receiving opening 1 a, the liquid mattercan be made to adversely affect the check valve V. The presentembodiment may also be practiced with the longitudinal direction seal 14in the examples described above being provided.

In an example shown in FIGS. 6B and 6C, the check valve V is disposed ata central portion (a front surface or a back surface) of the sealing bag1. In this example, the one bag sheet 11 is divided into two sheets of afirst sheet 11 a and a second sheet b. The first sheet 11 a and thesecond sheet b are made into a single bag seal by edges thereof beingsealed together, and the check valve V is fixed by being sandwichedbetween the first sheet 11 a and the second sheet 11 b. The seal betweenthe first sheet 11 a and the second sheet 11 b is the lateral directionseal 13 that traverses the check valve V. In this example, thedownstream side of the check valve V is positioned at an outer surface(an outer side of the bag) of the one sheet (the second sheet 11 b) andthe upstream side of the check valve V is positioned at an inner surface(an inner side of the bag) of the other sheet (the second sheet 11 b).The check valve V may be fixed regardless of its front and back sides,in the present example, the one base sheet 31 made of the nonwovenfabric, etc., is disposed at the inner surface side of the bag. Althoughin a case where the check valve V is fixed so that the one base sheet 31is positioned at the side facing the first sheet 11 a, when a food iscontained in the sealing bag 1 and heating by a microwave oven isperformed, the one base sheet 31 of the check valve V may be pressedagainst the first sheet 11 a due to air expanded by heating and the airmay not be evacuated satisfactorily, but by disposing the one base sheet31 at the inner side of the bag, the expanded air inside the bag can beevacuated satisfactorily. In particular, in the present example, theheat sealed portion of the lateral direction seal 13 that was necessaryfor fixing the check valve V by adhesion to the sealing bag 1 in theprevious examples is made unnecessary. As a result, evacuation withlower pressure is made possible, and in a case of practice, for example,as a bag that contains coffee beans, powder detergent, or other articlethat generates gas and is capable of suppressing expansion of the bag byevacuation of the gas generated from the article to the outside of thebag, the gas can be evacuated with the initial pressure of the evacuatedgas being low.

Also, as the second sheet 11 b, a sheet that is heat sealable at bothsurfaces is preferably adopted. Specifically, use of a coextruded filmwith both surfaces being made of polyethylene films is preferable. Thisis because the second sheet 11 b is heat sealed at one surface (theouter surface in the figure) to the first sheet 11 a that includes thelateral direction seal 13 and is sealed at the other surface (the innersurface in the figure) to the other bag sheet 12. In a case where sheetthat can be heat sealed at only one side is used, heat sealing can beperformed by folding back the edge to be sealed as in the example ofFIG. 5. Also, by using a sheet with which both surfaces are made ofpolyethylene films, etc., and heat sealing can be performed at bothsurfaces, the folding back is made unnecessary in the example of FIG. 5as well.

The present embodiment can also be practiced with the longitudinaldirection seal 14 of the previous examples being provided.

Another embodiment shall now be described based on FIG. 7. In thisexample, a portion of the check valve V of FIG. 1 is changed and thechanged portion shall mainly be described below with the portions notbeing described being the same as in the check valve V of FIG. 1.

In the present example, the one base sheet 31 is made of two types ofsheets. In detail, of the one base sheet 31, a sheet 31 a positioned atthe upstream side is, as in the example of FIG. 1, the gas flow passageportion 31 a and is made of the sheet of nonwoven fabric, etc., havinggas permeability. Unlike the previous example, the downstream side sheet31 d is made of a gastight sheet 31 d. End portions of the gas flowpassage portion 31 a and the gastight sheet 31 d are adhered with theupstream end 4 a 1 of the upstream valve body sheet 4 a at an adheredportion s1.

Although in the example of FIG. 1, the other base sheet 32 is madeshorter than the one base sheet 31 to form an air passage, in thepresent example, the other base sheet 32 and the one base sheet 31 aremade the same in size and whole perimeters thereof are adhered to form awhole perimeter adhered portion s3.

As in the example in FIG. 1, a sheet with gastightness is adopted as theother base sheet 32 and a slit or other outlet 32 b of suitable shape isformed as the outlet at the downstream end side. The outlet 32 b isdisposed further downstream (to the right in the figure) than thedownstream end 4 a 2 of the upstream valve body sheet 4 a and theupstream end 4 b 1 of the downstream valve body sheet 4 b.

As shown in FIG. 7D, the check valve V may be disposed inside of thesealing bag 1. This check valve V is disposed so as to cover, from aninner side, a bag vent hole 17 provided in the back bag sheet 12 of thesealing bag 1 and a whole perimeter thereof is adhered to the back bagsheet 12. The adhesion may be performed in common with the wholeperimeter adhered portion s3 or be performed by sealing separately.Although the outlet 32 b and the bag vent hole 17 are disposed at thesame position in the figure, these may be disposed at differentpositions as long as these are within the range of the whole perimeteradhered portion s3.

In evacuating air inside the sealing bag 1, the air enters into thecheck valve V from the gas flow passage portion 31 a and flows out tothe outside from the bag vent hole 17 via the outlet 32 b. When airtends to flow in from the outside, the inside of the check valve is putin a negative pressure state and the upstream valve body sheet 4 a andthe downstream valve body sheet 4 b closely contact the other base sheet32 to close the flow path.

Also, the check valve V may be disposed at an outside portion of thesealing bag 1 as shown in FIG. 7E. This check valve V is disposed so asto cover the bag vent hole 17, provided in the back bag sheet 12 of thesealing bag 1, from the outer side and the whole perimeter thereof isadhered to the back bag sheet 12 . The adhesion may be performed incommon with the whole perimeter adhered portion s3 or be performed bysealing separately. Although the gas flow passage portion 31 a and thebag vent hole 17 are disposed at the same position in the figure, thesemay be disposed at different positions as long as these are within therange of the whole perimeter adhered portion s3.

In evacuating air inside the sealing bag 1, the air enters into thecheck valve V from the bag vent hole 17 via the gas flow passage portion31 a and flows out to the outside from the outlet 32 b. When air tendsto flow in from the outside, the inside of the check valve is put in anegative pressure state and the upstream valve body sheet 4 a and thedownstream valve body sheet 4 b closely contact the other base sheet 32to close the flow path.

In either case of fixing the check valve V to the inside or outside ofthe sealing bag 1, the check valve V and the bag vent hole 17 may bedisposed on the front bag sheet 11.

Although in FIG. 7, the vertical length is exaggerated, in actuality,the respective sheets are practically in contact constantly and merely asmall gap opens only when air flows through.

In any of the embodiments, bent seals s4 and s5 may be applied to thecheck valve V of the present application so as to form a flow path ofzigzag form in a plan view. A specific example is shown in FIG. 8. Withthis example, a portion of the example of FIG. 7 is changed and only thechanged portion shall be described below with the portions not beingdescribed being the same as those in the example of FIG. 7.

As in the example of FIG. 1, with the check valve V of the presentexample, the other base sheet 32 is made shorter than the one base sheet31 and a space between the other base sheet 32 and the whole perimeteradhered portion s3 is used as the outlet 32 b. Needless to say, anoutlet 32 b such as that of the example of FIG. 7 may also be applied.

The bent seals s4 and s5 are formed across substantially an entirelength of the check valve V from the upstream end to the downstream endand adhere the three components of the one base sheet 31, the valve bodysheets 4, and the other base sheet 32 in the front/back direction.Although this check valve V adopts a nonwoven fabric or other sheet withgas permeability as in the gas flow passage portion 31 a of FIG. 7B,unlike FIG. 7B, crosshatching is not applied in the plan view of FIG. 8Ain order to show the bent seals s4 and s5 in a clear manner.

In the present example, the two bent seals s4 and s5 are formed, and inthe gas flow passage portion 31 a, an interval between the two bentseals s4 and s5 is increased gradually toward the upstream side (theleft side in the figure) so as to spread in a funnel-like manner. Air isthereby made to enter satisfactorily into the check valve V from the gasflow passage portion 31 a. At the portion with the valve body sheets 4,the two bent seals s4 and s5 are bent or curved while maintaining anarrow interval and extend toward the downstream side (the right side inthe figure). The two bent seals s4 and s5 differ in length, and the onebent seal s4 disappears upon entering the downstream valve body sheet 4b beyond the upstream valve body sheet 4 a. The other bent seal s5extends to the downstream end of the other base sheet 32 and thendisappears. The bent seals s4 and s5 are not formed at the outlet 32 bbetween the downstream end of the other base sheet 32 and the wholeperimeter adhered portion s3. This is done so that air is evacuatedsatisfactorily from the outlet 32 b. Of course, the above descriptiondescribes merely one example of the bent seals s4 and s5, and anyarrangement that weakens a rectilinearly progressing property of air andnarrows the flow path at the portion provided with the valve body sheets4 and spreads the flow path near the upstream end and the downstream endto smoothen the flow of air into and out of the check valve V suffices.Also, although the two bent seals s4 and s5 are formed, only one may beformed instead. In this case, an interval between the single bent sealand the whole perimeter adhered portion s3 becomes the flow path.Oppositely, three or more bent seals maybe used and used in combinationwith a point seal, etc., is also possible. Also, the shapes of the onebase sheet 31 and the other base sheet 32 may be cut along the shapes ofthe bent seals s4 and s5 so that the bent seals s4 and s5 serve incommon as portions of the whole perimeter adhered portion s3.

Further in the present example, a small amount of a silicone liquid orother inert substance 8 is disposed between the valve body sheets 4 andthe other base sheet 32 at an intermediate portion of the flow pathbetween the two bent seals s4 and s5. Close contact of the upstreamvalve body sheet 4 a and the other base sheet 32 is thereby increasedwhen the two components contact closely to close the flow path tothereby prevent leakage of air. Although the silicone oil or other inertsubstance 8 is thus disposed only between the upstream valve body sheet4 a and the other base sheet 32 in the present example, it may also bedisposed between the downstream valve body sheet 4 b and the other basesheet 32.

As in the example of FIG. 7, the present check valve V may also bedisposed either at the inside or the outside of the sealing bag 1 andprevents the reverse flow of a fluid and allows only the flow of thefluid in one direction (from the inner side to the outer side of the bagin the present example) by the same actions as those of the check valveV of FIG. 7. An example of fixing to the outer side of the bag sheet 12of the sealing bag 1 is shown in FIG. 8D.

As described above, with the present check valve V, the flow path of airis arranged in a maze-like manner by providing the bent seals s4 and s5and thus even in the case air flows in the positive direction, slightresistance arises. The degree of resistance can be changed variously bythe shapes and sizes of the bent seals s4 and s5 and can be adjustedaccording to the application. For example, in a case where the checkvalve V is used in a sealing bag that contains a food, a vapor that isgenerated from the food during thawing or heating by a microwave ovencan be released to the outside of the sealing bag by the check valve Vand by providing the bent seals s4 and s5, resistance against theevacuation of air is provided so that the vapor is evacuated out of thebag gradually. The food can thereby be steamed, and a thawing procedurefor preparing a more delicious meal can thus be performed with themicrowave oven. The shapes and sizes (lengths, widths) of the bent sealss4 and s5 can thus be changed as suited according to an air evacuationrate that is required.

An example is shown in FIG. 9A, wherein a different valve body sheet 91from the valve body sheets 4 a and 4 b is provided. The new valve bodysheet 91 is disposed between the valve body sheets 4 a and 4 b and theother base sheet 32 inside of the check valve V and is made closelycontactable with at least one of either the valve body sheet 4 a or 4 band the new valve body sheet 91 cooperates with the valve body sheets 4a and 4 b to perform passage and reverse flow prevention of a fluid. Thenew valve body sheet 91 may also be adopted in other embodiments of thepresent invention.

In the examples of FIG. 7 and FIG. 8, the one base sheet 31 is dividedinto the gas flow passage portion 31 a such as a nonwoven fabric, etc.and the gastight sheet 31 d, the entire one base sheet 31 may be made ofa nonwoven fabric or other material with gas permeability and only adownstream portion thereof may be coated with a covering sheet 92 withgastightness as shown in FIG. 9B. By making the entire one base sheet 31from the nonwoven fabric, etc., a situation where the valve body sheets4 a and 4 b closely contacted unnecessarily with the one base sheet 31and not providing the effect of the check valve can be prevented. Thecovering sheet 92 can be set freely in thickness, etc., and by using ahard sheet of comparatively large thickness, bending or twisting due topressing of the check valve V by contents of the sealing bag can beprevented to protect the valve and make the functions thereof be exertedreliably.

By providing the check valve V such as those described above, thecertainty of the checking effect can be improved while avoiding increaseof the production cost of the check valve V as much as possible, andvarious sealing bags 1 with the check valve V fixed can be made betterthan conventional arrangements.

In particular, in a case where the object contained in the sealing bag 1is a food or other readily degradable object, an effect of preventingoxidation of the contained object arises because the article containingportion 2 can be evacuated smoothly and a contribution can thus be madeto maintenance of freshness.

DESCRIPTION OF THE REFERENCE NUMERALS

1 Sealing Bag

11 Front Bag Sheet

12 Back Bag Sheet

13 Lateral Direction Seal

14 Longitudinal Direction Seal

141 Upstream End of Longitudinal Direction Seal

2 Article Containing Portion

3 a Gas Flow Passage Space

31 One Base Sheet

31 a Gas Flow Passage Portion

32 Other Base Sheet

4 Valve Body Sheet

4 a Upstream Valve Body Sheet

4 a 1 Upstream End of Upstream Valve Body Sheet

4 a 2 Downstream End of Upstream Valve Body Sheet

4 b Downstream Valve Body Sheet

4 b 1 Upstream End of Downstream Valve Body Sheet

4 b 2 Downstream End of Downstream Valve Body Sheet

4 b 3 Non-contacting Portion of Downstream Valve Body Sheet

V Check Valve

1. A check valve formed by overlapping a plurality of sheets, having agas flow passage space, which is a space through which gas passes,formed between the sheets, and being capable of allowing passage of gasflow in a positive direction from an inlet to an outlet and blocking gasflow in a reverse direction from the outlet to the inlet by opening andclosing of the gas flow passage space, wherein the check valve iscomprised of a plurality of base sheets made of resin, and a pluralityof flexible valve body sheets made of resin; the plurality of basesheets being disposed to face each other in a front/back direction, atleast two sheets of the plurality of valve body sheets forming a singleset comprising an upstream valve body sheet disposed at an upstream sideand a downstream valve body sheet disposed at a downstream side on abasis of the positive gas flow direction, each of the valve body sheetsthat forms the single set being adhered to at least one base sheet, theadhesion being achieved so that the respective valve body sheets arealigned in series in a gas flow direction during evacuation and so asnot to be overlapped in the front/back direction, the adhesion of theupstream valve body sheet to the one base sheet being achieved at anupstream end side with a downstream end side being made movable withrespect to the base sheets, the adhesion of the downstream valve bodysheet being achieved at a downstream end side with an upstream end sidebeing movable with respect to one base sheet, and at least a portion ofthe single set of valve body sheets being capable of contacting closelyand separating with respect to another base sheet or with respect to avalve body sheet different from the single set of valve body sheets anddisposed on the opposite side of the one base sheet across the singleset of valve body sheets, thereby allowing passage of gas flow in thepositive direction and block gas flow in the reverse direction.
 2. Thecheck valve according to claim 1, wherein a portion of the one basesheet is arranged as a gas flow passage portion having gas permeabilityof allowing gas flow in the positive direction to pass through in thefront/back direction, the gas flow passage portion being an inletthrough which the gas flow in the positive direction flows into thecheck valve, and the gas flow passage portion being disposed at aposition of the one base sheet that is further upstream than a positionmatching the upstream end of the upstream valve body sheet in thefront/back direction.
 3. The check valve according to claim 2, whereinthe one base sheet comprises the gas flow passage portion and anotherportion, the another portion having gastightness.
 4. The check valveaccording to claim 1, wherein the outlet through which gas flow in thepositive direction flows out from the inside of the check valve isdisposed at other base sheet side, the outlet being formed by making theother base sheet smaller than the one base sheet or by providing anopening in the other base sheet, and the outlet being disposed at aposition of the one base sheet that is further downstream than aposition matching the downstream end of the upstream valve body sheet inthe front/back direction.
 5. The check valve according to claim 4,wherein a bent seal is formed between the inlet and the outlet, the bentseal being adhesion of the one base sheet, the valve body sheets, andthe other base sheet in the front/back direction, and the bent sealshaping bent so that a flow path inside the check valve from the inletto the outlet becomes a zigzagging flow path in a plan view of thesheets.
 6. The check valve according to claim 5, wherein a siliconeliquid or other inert substance is disposed inside a flow path, definedby the bent seal, between the valve body sheets and the other basesheet.
 7. The check valve according to claim 1, wherein the one basesheet has gas permeability across its entire surface, a portion of thegas-permeable one base sheet is arranged as a gas flow passage portionthrough which gas flow in the positive direction passes in thefront/back direction, the gas flow passage portion being a portion ofthe one base sheet that is further upstream than a position matching theupstream end of the upstream valve body sheet in the front/backdirection.
 8. The check valve according to claim 2, wherein the gas flowpassage portion of the one base sheet is provided with a nonwovenfabric.
 9. The check valve according to claim 1, wherein the one basesheet is made of a nonwoven fabric having gas permeability across itsentire surface, a portion of the gas-permeable one base sheet isarranged as a gas flow passage portion through which gas flow in thepositive direction passes in the front/back direction, a portion of theone base sheet except the gas flow passage portion being covered by acovering sheet having gastightness.
 10. The check valve according toclaim 1, wherein the check valve is used by being fixed to a sealing baghaving an article containing portion, the article containing portionbeing capable of ventilation to the outside of the bag to evacuate gaspresent in the article containing portion to the outside of the bag. 11.A sealing bag having the check valve according to claim 4 fixed thereto,wherein the sealing bag is comprised of a flexible bag sheet made ofresin, the bag sheet being adhered so that a portion except an articlereceiving opening and a portion to which the check valve is fixed isseparated in a gastight manner from the outside of the bag, and a wholeperimeter of the check valve is adhered to an inner side or an outerside of the bag sheet.
 12. A sealing bag having the check valveaccording to claim 7 fixed thereto, wherein the sealing bag is comprisedof a flexible bag sheet made of resin, the bag sheet being adhered sothat a portion except an article receiving opening and a portion towhich the check valve is fixed is separated in a gastight manner fromthe outside of the bag, the check valve, sandwiched by the bag sheet,having an upstream end positioned inside the article containing portionand a downstream end positioned outside the article containing portionon a basis of a gas flow direction during evacuation, a portion at anupstream end side of the other base sheet of the check valve beingadhered to a surface of the bag sheet that is an inner surface facingthe other base sheet, a gas flow passage portion of the one base sheetof the check valve being exposed to a space in the article containingportion that is capable of containing an article, a lateral directionseal being formed by adhesion of the bag sheet, the lateral directionseal being formed to traverse the check valve in a width direction, alongitudinal direction seal being formed additionally by the adhesion ofthe bag sheet, the longitudinal direction seal being in a directionintersecting the lateral direction seal and extended more to theupstream side than the lateral direction seal on a basis of a gas flowdirection during evacuation inside the check valve, the longitudinaldirection seal being provided sandwiching the check valve and beingspaced by an interval wider than a width dimension of the check valve toform a single set by two, and an upstream end of the longitudinaldirection seal being positioned further upstream, on a basis of the gasflow direction during evacuation inside the check valve, than a lowerend of a portion, of the gas flow passage portion in the one base sheet,which is defined by the lateral direction seal and through which airpractically flows.
 13. A method for producing the check valve accordingto claim 1, wherein elongate sheets supplied continuously in alongitudinal direction are used as the base sheet and the valve bodysheet, and the respective valve body sheets forming a single set aresupplied as a single elongate sheet that is thereafter cut in two in awidth direction and overlapped with the one base sheet.
 14. A method forproducing a sealing bag having a check valve fixed thereto, wherein thecheck valve is comprised of flexible base sheets made of resin; and aplurality of valve body sheets, one base sheet of the base sheets hasgas permeability across its entire surface, the base sheets are disposedto face each other in a front/back direction, at least two sheets of theplurality of valve body sheets forming a single set comprising anupstream valve body sheet disposed at an upstream side and a downstreamvalve body sheet disposed at a downstream side on a basis of a gas flowdirection during evacuation, each of the valve body sheets that formsthe single set are adhered at least to the one base sheet, the adhesionis achieved so that the respective valve body sheets are aligned inseries in the gas flow direction during evacuation and so as not to beoverlapped in the front/back direction, the adhesion of the upstreamvalve body sheet to the one base sheet is achieved at an upstream endside with a downstream end side being made movable with respect to thebase sheets, the adhesion of the downstream valve body sheet is achievedat a downstream end side with an upstream end side being movable withrespect to the base sheets, and the respective ends of the valve bodysheets that are made movable with respect to the base sheets are capableof closely contacting the other base sheet or a valve body sheet that isdifferent from the valve body sheets forming the single set and isadhered to the other base sheet; and a flexible elongate sheet made ofresin and supplied continuously in a longitudinal direction is used as abag sheet, the method for producing a sealing bag comprising the stepsof: sandwiching the check valve by the bag sheet; forming a lateraldirection seal traversing the check valve in a width direction byadhesion of the bag sheet; and forming a longitudinal direction seal byadhesion of the bag sheet; the longitudinal direction seal formed in thesteps, being in a direction intersecting the lateral direction seal andextended more to the upstream side on the basis of the gas flowdirection during evacuation inside the check valve than the lateraldirection seal, the longitudinal direction seal being providedsandwiching the check valve and spaced by an interval wider than a widthdimension of the check valve to form a single set by two, and anupstream end of the longitudinal direction seal being positioned furtherupstream, on a basis of the gas flow direction during evacuation insidethe check valve, than a lower end of a portion, of the gas flow passageportion in the one base sheet, which is defined by the lateral directionseal and through which air practically flows.